1. Field of the Invention
The present invention relates to antennae used in wireless communication, adjustment methods for such antennae, and electronic devices in which such antennae are implemented.
2. Description of the Related Art
In recent years, electronic devices such as personal computers that are provided with wireless communication functionality, such as wireless LAN or Bluetooth®, are becoming widespread. Wireless communication over wireless LAN, Bluetooth, and so on is carried out using radio waves in, for example, the 2.5 GHz band, the 5 GHz band, or the like. A personal computer provided with such wireless communication functionality integrates an antenna for wireless communication; various types of antennae are used depending on the model of the computer, such as a dipole antenna, a helical antenna, a slot antenna, an inverted-F antenna, and so on.
Due to reductions in the sizes of electronic devices, it is becoming necessary to implement these various types of antennae in areas having limited amounts of space, and there is also a demand for reductions in the costs thereof. As a result, attempts are being made to reduce costs by implementing antennae as patterned shapes upon the boards of wireless module chips, rather than implementing the antennae separately.
However, in the case where an antenna is implemented in an electronic device such as a personal computer, the frequency characteristics of the antenna change depending on the components that are located in the periphery of the antenna. There is thus a problem in that the frequency characteristics obtained when the antenna is in a standalone state differ from the frequency characteristics obtained when the antenna is implemented. Thus far, configurations have been such that changes in the frequency characteristics of an antenna occurring due to the antenna being implemented in an electronic device are absorbed by the antenna. For example, desired frequency characteristics are achieved for an antenna when the antenna is implemented by using various methods, such as adjusting the shape of the antenna.
U.S. Pat. No. 5,483,249 discloses a technique for adjusting a resonation frequency by changing the position of a through-hole in order to adjust the length of the short stub portion of a radiating element that functions as a cavity resonator. The adjustment of the resonation frequency is carried out by changing the length of the stub that configures part of the radiating element.
Japanese Patent Laid-Open No. 09-162642 discloses a technique for adjusting a resonation frequency, in which multiple stubs having free ends are formed connected to a microstrip line-type resonator in advance, and are shorted through soldering in a state in which opening patterns are formed in the vicinities of the ends of the stubs; the resonating frequency is then adjusted by changing the capacities of the stubs connected to the resonator. Likewise, the adjustment of the resonation frequency is carried out by changing the length of the stub that configures part of the radiating element.
However, with the stated past methods of bringing a change in the frequency characteristics of an antenna, occurring when the antenna is implemented, in line with desired characteristics by adjusting the shape of the antenna, the environment in which the antenna is implemented differs depending on the type of electronic device, and thus the change in frequency characteristics occurring when the antenna is implemented is not always the same. There is thus a problem in that the same antenna cannot be used in different types of electronic devices.
The present invention provides a technique for enabling the same antenna to be used in different types of electronic devices while improving the reflection characteristics when the antenna is implemented.